/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//   Thomas H�vel (mailto:Thomas.Hoevel@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
#if GDI
using System.Drawing;
using System.Drawing.Imaging;
#endif
#if WPF
using System.Windows.Media;
using System.Windows.Media.Imaging;
#endif
using PdfSharp.Drawing;
using PdfSharp.Fonts.TrueType;
using PdfSharp.Internal;
using PdfSharp.Pdf.Filters;
using silverPDF._compatebleLayer;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Represents an image.
  /// </summary>
  public sealed class PdfImage2 : PdfXObject
  {
    /// <summary>
    /// Initializes a new instance of PdfImage from an XImage.
    /// </summary>
    public PdfImage2(PdfDocument document, XImage image)
      : base(document)
    {
      Elements.SetName(Keys.Type, "/XObject");
      Elements.SetName(Keys.Subtype, "/Image");

      this.image = image;

      ////// TODO: identify multiple used images. If the image already exists use the same XRef.
      ////this.defaultName = PdfImageTable.NextImageName;

      switch (this.image.Format.Guid.ToString("B").ToUpper())
      {
        // Pdf supports Jpeg, therefore we can write what we've read:
        case "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}":  //XImageFormat.Jpeg
          InitializeJpeg();
          break;

        // All other image formats are converted to PDF bitmaps:
        case "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}":  //XImageFormat.Png
        case "{B96B3CB0-0728-11D3-9D7B-0000F81EF32E}":  //XImageFormat.Gif
        case "{B96B3CB1-0728-11D3-9D7B-0000F81EF32E}":  //XImageFormat.Tiff
        case "{B96B3CB5-0728-11D3-9D7B-0000F81EF32E}":  //XImageFormat.Icon
          // TODO: possible optimization for PNG (do not decompress/recompress)???
          // TODO: try Jpeg for size optimization???
          InitializeNonJpeg();
          break;

        case "{84570158-DBF0-4C6B-8368-62D6A3CA76E0}":  //XImageFormat.Pdf:
          Debug.Assert(false, "XPdfForm not expected here.");
          break;

        default:
          Debug.Assert(false, "Unexpected image type.");
          break;
      }
    }

    /// <summary>
    /// Gets the underlying XImage object.
    /// </summary>
    public XImage Image
    {
      get { return this.image; }
    }
    XImage image;

    /// <summary>
    /// Returns 'Image'.
    /// </summary>
    public override string ToString()
    {
      return "Image";
    }

    /// <summary>
    /// Creates the keys for a JPEG image.
    /// </summary>
    void InitializeJpeg()
    {
      // PDF support JPEG, so there's not much to be done
      MemoryStream memory = new MemoryStream();
#if GDI
      image.gdiImage.Save(memory, ImageFormat.Jpeg);
#endif
#if WPF
      JpegBitmapEncoder encoder = new JpegBitmapEncoder();
      encoder.Frames.Add((BitmapFrame)BitmapFrame.Create(this.image.wpfImage));
      encoder.Save(memory);
#endif
      int streamLength = (int)memory.Length;
      byte[] imageBits = new byte[streamLength];
      memory.Seek(0, SeekOrigin.Begin);
      memory.Read(imageBits, 0, streamLength);
      memory.Close();

      Stream = new PdfStream(imageBits, this);

      Elements[Keys.Length] = new PdfInteger(streamLength);
      Elements[Keys.Filter] = new PdfName("/DCTDecode");
      Elements[Keys.Width] = new PdfInteger(image.PixelWidth);
      Elements[Keys.Height] = new PdfInteger(image.PixelHeight);
      Elements[Keys.BitsPerComponent] = new PdfInteger(8);
#if GDI
      if ((image.gdiImage.Flags & ((int)ImageFlags.ColorSpaceCmyk | (int)ImageFlags.ColorSpaceYcck)) != 0)
      {
        // TODO: Test with CMYK JPEG files
        // THHO: I only found ImageFlags.ColorSpaceYcck JPEG files ...
        Elements[Keys.ColorSpace] = new PdfName("/DeviceCMYK");
        if ((image.gdiImage.Flags & (int)ImageFlags.ColorSpaceYcck) != 0)
          Elements["/Decode"] = new PdfLiteral("[1 0 1 0 1 0 1 0]");  // Invert colors? Why??
      }
      else if ((image.gdiImage.Flags & (int)ImageFlags.ColorSpaceGray) != 0)
      {
        Elements[Keys.ColorSpace] = new PdfName("/DeviceGray");
      }
      else
      {
        Elements[Keys.ColorSpace] = new PdfName("/DeviceRGB");
      }
#endif
#if WPF
      // TODOWPF
      // WPFTHHO
#endif
    }

    /// <summary>
    /// Creates the keys for a FLATE image.
    /// </summary>
    void InitializeNonJpeg()
    {
#if GDI && !WPF
      bool hasMask = false;
      int pPdfVersion = this.Owner.Version;
      switch (image.gdiImage.PixelFormat)
      {
        case System.Drawing.Imaging.PixelFormat.Format24bppRgb:
          ReadTrueColorMemoryBitmap(3, 8, false);
          break;

        case System.Drawing.Imaging.PixelFormat.Format32bppRgb:
          ReadTrueColorMemoryBitmap(4, 8, false);
          break;

        case System.Drawing.Imaging.PixelFormat.Format32bppArgb:
        case System.Drawing.Imaging.PixelFormat.Format32bppPArgb:
          hasMask = true;
          ReadTrueColorMemoryBitmap(3, 8, true);
          break;

        case System.Drawing.Imaging.PixelFormat.Format8bppIndexed:
          ReadIndexedMemoryBitmap(8, ref hasMask);
          break;

        case System.Drawing.Imaging.PixelFormat.Format4bppIndexed:
          ReadIndexedMemoryBitmap(4, ref hasMask);
          break;

        case System.Drawing.Imaging.PixelFormat.Format1bppIndexed:
          ReadIndexedMemoryBitmap(1, ref hasMask);
          break;

        default:
#if DEBUGxxx
          image.image.Save("$$$.bmp", ImageFormat.Bmp);
#endif
          throw new NotImplementedException("Image format not supported.");
      }
#endif
#if WPF // && !GDI
      // WPFTHHO: Bitte pr�fen, siehe System.Windows.Media.PixelFormats
      bool hasMask = false;
      int pPdfVersion = this.Owner.Version;
      string format = image.wpfImage.Format.ToString();
      format = "Indexed8";
      switch (format)
      {
        case "Bgr24": //Format24bppRgb:
          ReadTrueColorMemoryBitmap(3, 8, false);
          break;

        //case .PixelFormat.Format32bppRgb:
        //  ReadTrueColorMemoryBitmap(4, 8, false);
        //  break;

        case "Bgra32":  //PixelFormat.Format32bppArgb:
          //case PixelFormat.Format32bppPArgb:
          hasMask = true;
          ReadTrueColorMemoryBitmap(3, 8, true);
          break;

        case "Bgr32": // StL: neu
          hasMask = false;
          ReadTrueColorMemoryBitmap(3, 8, true);
          break;

        case "Pbgra32": // StL: neu
          hasMask = false;
          ReadTrueColorMemoryBitmap(3, 8, true);
          break;

        case "Indexed8":  //Format8bppIndexed:
          ReadIndexedMemoryBitmap(8, ref hasMask);
          break;

        case "Indexed4":  //Format4bppIndexed:
          ReadIndexedMemoryBitmap(4, ref hasMask);
          break;

        case "Indexed2": // WPFTHHO gibt es das auch?
          ReadIndexedMemoryBitmap(2, ref hasMask);
          break;

        case "Indexed1":  //Format1bppIndexed:
          ReadIndexedMemoryBitmap(1, ref hasMask);
          break;

        default:
#if DEBUGxxx
          image.image.Save("$$$.bmp", ImageFormat.Bmp);
#endif
          throw new NotImplementedException("Image format not supported.");
      }
#endif
    }

    private int ReadWord(byte[] ab, int offset)
    {
      return (int)ab[offset] + 256 * (int)ab[offset + 1];
    }

    private int ReadDWord(byte[] ab, int offset)
    {
      return ReadWord(ab, offset) + 0x10000 * ReadWord(ab, offset + 2);
    }

    /// <summary>
    /// Reads images that are returned from GDI+ without color palette.
    /// </summary>
    /// <param name="components">4 (32bpp RGB), 3 (24bpp RGB, 32bpp ARGB)</param>
    /// <param name="bits">8</param>
    /// <param name="hasAlpha">true (ARGB), false (RGB)</param>
    private void ReadTrueColorMemoryBitmap(int components, int bits, bool hasAlpha)
    {
#if DEBUG_
      image.image.Save("$$$.bmp", ImageFormat.Bmp);
#endif
      int pdfVersion = this.Owner.Version;
      MemoryStream memory = new MemoryStream();
#if GDI
      image.gdiImage.Save(memory, ImageFormat.Bmp);
#endif
#if WPF
      // WPFTHHO: Bitte pr�fen
      BmpBitmapEncoder encoder = new BmpBitmapEncoder();
      encoder.Frames.Add((BitmapFrame)BitmapFrame.Create(this.image.wpfImage));
      encoder.Save(memory);
#endif
      int streamLength = (int)memory.Length;
      Debug.Assert(streamLength > 0, "Bitmap image encoding failed.");
      if (streamLength > 0)
      {
        byte[] imageBits = new byte[streamLength];
        memory.Seek(0, SeekOrigin.Begin);
        memory.Read(imageBits, 0, streamLength);
        memory.Close();

        int height = this.image.PixelHeight;
        int width = this.image.PixelWidth;

        // TODO: we could define structures for
        //   BITMAPFILEHEADER
        //   { BITMAPINFO }
        //   BITMAPINFOHEADER
        // to avoid ReadWord and ReadDWord ... (but w/o pointers this doesn't help much)

        if (ReadWord(imageBits, 0) != 0x4d42 || // "BM"
            ReadDWord(imageBits, 2) != streamLength ||
            ReadDWord(imageBits, 14) != 40 || // sizeof BITMAPINFOHEADER
            ReadDWord(imageBits, 18) != width ||
            ReadDWord(imageBits, 22) != height)
        {
          throw new NotImplementedException("ReadTrueColorMemoryBitmap: unsupported format");
        }
        if (ReadWord(imageBits, 26) != 1 ||
          (!hasAlpha && ReadWord(imageBits, 28) != components * bits ||
           hasAlpha && ReadWord(imageBits, 28) != (components + 1) * bits) ||
          ReadDWord(imageBits, 30) != 0)
        {
          throw new NotImplementedException("ReadTrueColorMemoryBitmap: unsupported format #2");
        }

        int nFileOffset = ReadDWord(imageBits, 10);
        int logicalComponents = components;
        if (components == 4)
          logicalComponents = 3;

        byte[] imageData = new byte[components * width * height];

        bool hasMask = false;
        bool hasAlphaMask = false;
        byte[] alphaMask = hasAlpha ? new byte[width * height] : null;
        MonochromeMask mask = hasAlpha ?
          new MonochromeMask(width, height) : null;

        int nOffsetRead = 0;
        if (logicalComponents == 3)
        {
          for (int y = 0; y < height; ++y)
          {
            int nOffsetWrite = 3 * (height - 1 - y) * width;
            if (hasAlpha)
              mask.StartLine(y);

            for (int x = 0; x < width; ++x)
            {
              imageData[nOffsetWrite] = imageBits[nFileOffset + nOffsetRead + 2];
              imageData[nOffsetWrite + 1] = imageBits[nFileOffset + nOffsetRead + 1];
              imageData[nOffsetWrite + 2] = imageBits[nFileOffset + nOffsetRead];
              if (hasAlpha)
              {
                mask.AddPel(imageBits[nFileOffset + nOffsetRead + 3]);
                alphaMask[nOffsetWrite / 3] = imageBits[nFileOffset + nOffsetRead + 3];
                if (!hasMask || !hasAlphaMask)
                {
                  if (imageBits[nFileOffset + nOffsetRead + 3] != 255)
                  {
                    hasMask = true;
                    if (imageBits[nFileOffset + nOffsetRead + 3] != 0)
                      hasAlphaMask = true;
                  }
                }
              }
              nOffsetRead += hasAlpha ? 4 : components;
              nOffsetWrite += 3;
            }
            nOffsetRead = 4 * ((nOffsetRead + 3) / 4); // Align to 32 bit boundary
          }
        }
        else if (components == 1)
        {
          // Grayscale
          throw new NotImplementedException("Image format not supported (grayscales).");
        }

        FlateDecode fd = new FlateDecode();
        if (hasMask)
        {
          // monochrome mask is either sufficient or
          // provided for compatibility with older reader versions
          byte[] maskDataCompressed = fd.Encode(mask.MaskData);
          PdfDictionary pdfMask = new PdfDictionary(this.document);
          pdfMask.Elements.SetName(Keys.Type, "/XObject");
          pdfMask.Elements.SetName(Keys.Subtype, "/Image");

          this.Owner.irefTable.Add(pdfMask);
          pdfMask.Stream = new PdfStream(maskDataCompressed, pdfMask);
          pdfMask.Elements[Keys.Length] = new PdfInteger(maskDataCompressed.Length);
          pdfMask.Elements[Keys.Filter] = new PdfName("/FlateDecode");
          pdfMask.Elements[Keys.Width] = new PdfInteger(width);
          pdfMask.Elements[Keys.Height] = new PdfInteger(height);
          pdfMask.Elements[Keys.BitsPerComponent] = new PdfInteger(1);
          pdfMask.Elements[Keys.ImageMask] = new PdfBoolean(true);
          Elements[Keys.Mask] = pdfMask.Reference;
        }
        if (hasMask && hasAlphaMask && pdfVersion >= 14)
        {
          // The image provides an alpha mask (requires Arcrobat 5.0 or higher)
          byte[] alphaMaskCompressed = fd.Encode(alphaMask);
          PdfDictionary smask = new PdfDictionary(this.document);
          smask.Elements.SetName(Keys.Type, "/XObject");
          smask.Elements.SetName(Keys.Subtype, "/Image");

          this.Owner.irefTable.Add(smask);
          smask.Stream = new PdfStream(alphaMaskCompressed, smask);
          smask.Elements[Keys.Length] = new PdfInteger(alphaMaskCompressed.Length);
          smask.Elements[Keys.Filter] = new PdfName("/FlateDecode");
          smask.Elements[Keys.Width] = new PdfInteger(width);
          smask.Elements[Keys.Height] = new PdfInteger(height);
          smask.Elements[Keys.BitsPerComponent] = new PdfInteger(8);
          smask.Elements[Keys.ColorSpace] = new PdfName("/DeviceGray");
          Elements[Keys.SMask] = smask.Reference;
        }

        byte[] imageDataCompressed = fd.Encode(imageData);

        Stream = new PdfStream(imageDataCompressed, this);
        Elements[Keys.Length] = new PdfInteger(imageDataCompressed.Length);
        Elements[Keys.Filter] = new PdfName("/FlateDecode");
        Elements[Keys.Width] = new PdfInteger(width);
        Elements[Keys.Height] = new PdfInteger(height);
        Elements[Keys.BitsPerComponent] = new PdfInteger(8);
        // TODO: CMYK
        Elements[Keys.ColorSpace] = new PdfName("/DeviceRGB");
        if (image.Interpolate)
          Elements[Keys.Interpolate] = PdfBoolean.True;
      }
    }

    /* BITMAPINFOHEADER struct and byte offsets:
        typedef struct tagBITMAPINFOHEADER{
          DWORD  biSize;           // 14
          LONG   biWidth;          // 18
          LONG   biHeight;         // 22
          WORD   biPlanes;         // 26
          WORD   biBitCount;       // 28
          DWORD  biCompression;    // 30
          DWORD  biSizeImage;      // 34
          LONG   biXPelsPerMeter;  // 38
          LONG   biYPelsPerMeter;  // 42
          DWORD  biClrUsed;        // 46
          DWORD  biClrImportant;   // 50
        } BITMAPINFOHEADER, *PBITMAPINFOHEADER; 
    */

    private void ReadIndexedMemoryBitmap(int bits, ref bool hasAlpha)
    {
#if DEBUG_
      image.image.Save("$$$.bmp", ImageFormat.Bmp);
#endif
      int pdfVersion = this.Owner.Version;
      int firstMaskColor = -1, lastMaskColor = -1;
      bool segmentedColorMask = false;

      MemoryStream memory = new MemoryStream();
#if GDI
      image.gdiImage.Save(memory, ImageFormat.Bmp);
#endif
#if WPF
      // WPFTHHO: StL: keine Ahnung ob das so stimmt.
      BmpBitmapEncoder encoder = new BmpBitmapEncoder();
      encoder.Frames.Add((BitmapFrame)BitmapFrame.Create(this.image.wpfImage));
      encoder.Save(memory);
#endif
      int streamLength = (int)memory.Length;
      Debug.Assert(streamLength > 0, "Bitmap image encoding failed.");
      if (streamLength > 0)
      {
        byte[] imageBits = new byte[streamLength];
        memory.Seek(0, SeekOrigin.Begin);
        memory.Read(imageBits, 0, streamLength);
        memory.Close();

        int height = this.image.PixelHeight;
        int width = this.image.PixelWidth;

        if (ReadWord(imageBits, 0) != 0x4d42 || // "BM"
          ReadDWord(imageBits, 2) != streamLength ||
          ReadDWord(imageBits, 14) != 40 || // sizeof BITMAPINFOHEADER
#if WPF
          // TODOWPF: bug with height and width
          false)
#else
          ReadDWord(imageBits, 18) != width ||
          ReadDWord(imageBits, 22) != height)
#endif
        {
          throw new NotImplementedException("ReadIndexedMemoryBitmap: unsupported format");
        }
#if WPF
        // TODOWPF: bug with height and width
        width = ReadDWord(imageBits, 18);
        height = ReadDWord(imageBits, 22);
#endif
        if (ReadWord(imageBits, 26) != 1 ||
            ReadWord(imageBits, 28) != bits ||
            ReadDWord(imageBits, 30) != 0)
        {
          throw new NotImplementedException("ReadIndexedMemoryBitmap: unsupported format #2");
        }

        int bytesFileOffset = ReadDWord(imageBits, 10);
        int bytesColorPaletteOffset = 0x36; // GDI+ always returns Windows bitmaps: sizeof BITMAPFILEHEADER + sizeof BITMAPINFOHEADER
        int paletteColors = ReadDWord(imageBits, 46);
        if ((bytesFileOffset - bytesColorPaletteOffset) / 4 != paletteColors)
        {
          throw new NotImplementedException("ReadIndexedMemoryBitmap: unsupported format #3");
        }

        MonochromeMask mask = new MonochromeMask(width, height);

        byte[] paletteData = new byte[3 * paletteColors];
        for (int color = 0; color < paletteColors; ++color)
        {
          paletteData[3 * color] = imageBits[bytesColorPaletteOffset + 4 * color + 2];
          paletteData[3 * color + 1] = imageBits[bytesColorPaletteOffset + 4 * color + 1];
          paletteData[3 * color + 2] = imageBits[bytesColorPaletteOffset + 4 * color + 0];
          if (imageBits[bytesColorPaletteOffset + 4 * color + 3] < 128)
          {
            // We treat this as transparency:
            if (firstMaskColor == -1)
              firstMaskColor = color;
            if (lastMaskColor == -1 || lastMaskColor == color - 1)
              lastMaskColor = color;
            if (lastMaskColor != color)
              segmentedColorMask = true;
          }
          else
          {
            // We treat this as opacity:
          }
        }

        // NYI: (no sample found where this was required) 
        // if (segmentedColorMask = true)
        // { ... }

        FlateDecode fd = new FlateDecode();
        PdfDictionary colorPalette = new PdfDictionary(this.document);
        // TODO: decide at run-time if compression makes sense
#if false
        // Create uncompressed color palette:
        colorPalette.CreateStream(paletteData);
        colorPalette.Elements[Keys.Length] = new PdfInteger(paletteData.Length);
#else
        // Create compressed color palette:
        byte[] packedPaletteData = fd.Encode(paletteData);
        colorPalette.CreateStream(packedPaletteData);
        colorPalette.Elements[Keys.Length] = new PdfInteger(packedPaletteData.Length);
        colorPalette.Elements[Keys.Filter] = new PdfName("/FlateDecode");
#endif
        this.Owner.irefTable.Add(colorPalette);

        byte[] imageData = new byte[1 * width * height];

        int bytesOffsetRead = 0;
        if (bits == 8 || bits == 4 || bits == 1)
        {
          int bytesPerLine = (width * bits + 7) / 8;
          for (int y = 0; y < height; ++y)
          {
            mask.StartLine(y);
            int bytesOffsetWrite = (height - 1 - y) * ((width * bits + 7) / 8);
            for (int x = 0; x < bytesPerLine; ++x)
            {
              imageData[bytesOffsetWrite] = imageBits[bytesFileOffset + bytesOffsetRead];
              if (firstMaskColor != -1)
              {
                int n = imageBits[bytesFileOffset + bytesOffsetRead];
                if (bits == 8)
                {
                  // TODO???: segmentedColorMask == true => falsche Maske NYI
                  mask.AddPel((n >= firstMaskColor) && (n <= lastMaskColor));
                }
                else if (bits == 4)
                {
                  // TODO???: segmentedColorMask == true => falsche Maske NYI
                  int n1 = (n & 0xf0) / 16;
                  int n2 = (n & 0x0f);
                  mask.AddPel((n1 >= firstMaskColor) && (n1 <= lastMaskColor));
                  mask.AddPel((n2 >= firstMaskColor) && (n2 <= lastMaskColor));
                }
                else if (bits == 1)
                {
                  // TODO???: segmentedColorMask == true => bad mask NYI
                  for (int bit = 1; bit <= 8; ++bit)
                  {
                    int n1 = (n & 0x80) / 128;
                    mask.AddPel((n1 >= firstMaskColor) && (n1 <= lastMaskColor));
                    n *= 2;
                  }
                }
              }
              bytesOffsetRead += 1;
              bytesOffsetWrite += 1;
            }
            bytesOffsetRead = 4 * ((bytesOffsetRead + 3) / 4); // Align to 32 bit boundary
          }
        }
        else
        {
          throw new NotImplementedException("ReadIndexedMemoryBitmap: unsupported format #3");
        }

        if (firstMaskColor != -1 &&
          lastMaskColor != -1)
        {
          // Color mask requires Reader 4.0 or higher:
          if (!segmentedColorMask && pdfVersion >= 13)
          {
            PdfArray array = new PdfArray(this.document);
            array.Elements.Add(new PdfInteger(firstMaskColor));
            array.Elements.Add(new PdfInteger(lastMaskColor));
            Elements[Keys.Mask] = array;
          }
          else
          {
            // Monochrome mask
            byte[] maskDataCompressed = fd.Encode(mask.MaskData);
            PdfDictionary pdfMask = new PdfDictionary(this.document);
            pdfMask.Elements.SetName(Keys.Type, "/XObject");
            pdfMask.Elements.SetName(Keys.Subtype, "/Image");

            this.Owner.irefTable.Add(pdfMask);
            pdfMask.Stream = new PdfStream(maskDataCompressed, pdfMask);
            pdfMask.Elements[Keys.Length] = new PdfInteger(maskDataCompressed.Length);
            pdfMask.Elements[Keys.Filter] = new PdfName("/FlateDecode");
            pdfMask.Elements[Keys.Width] = new PdfInteger(width);
            pdfMask.Elements[Keys.Height] = new PdfInteger(height);
            pdfMask.Elements[Keys.BitsPerComponent] = new PdfInteger(1);
            pdfMask.Elements[Keys.ImageMask] = new PdfBoolean(true);
            Elements[Keys.Mask] = pdfMask.Reference;
          }
        }

        byte[] imageDataCompressed = fd.Encode(imageData);

        Stream = new PdfStream(imageDataCompressed, this);
        Elements[Keys.Length] = new PdfInteger(imageDataCompressed.Length);
        Elements[Keys.Filter] = new PdfName("/FlateDecode");
        Elements[Keys.Width] = new PdfInteger(width);
        Elements[Keys.Height] = new PdfInteger(height);
        Elements[Keys.BitsPerComponent] = new PdfInteger(bits);
        PdfArray array2 = new PdfArray(this.document);
        array2.Elements.Add(new PdfName("/Indexed"));
        // TODO: CMYK
        array2.Elements.Add(new PdfName("/DeviceRGB"));
        array2.Elements.Add(new PdfInteger(paletteColors - 1));
        array2.Elements.Add(colorPalette.Reference);
        Elements[Keys.ColorSpace] = array2;
      }
    }

    /// <summary>
    /// Common keys for all streams.
    /// </summary>
    public sealed new class Keys : PdfXObject.Keys
    {
      /// <summary>
      /// (Optional) The type of PDF object that this dictionary describes;
      /// if present, must be XObject for an image XObject.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Optional)]
      public const string Type = "/Type";

      /// <summary>
      /// (Required) The type of XObject that this dictionary describes;
      /// must be Image for an image XObject.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Required)]
      public const string Subtype = "/Subtype";

      /// <summary>
      /// (Required) The width of the image, in samples.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string Width = "/Width";

      /// <summary>
      /// (Required) The height of the image, in samples.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string Height = "/Height";

      /// <summary>
      /// (Required for images, except those that use the JPXDecode filter; not allowed for image masks)
      /// The color space in which image samples are specified; it can be any type of color space except
      /// Pattern. If the image uses the JPXDecode filter, this entry is optional:
      /// � If ColorSpace is present, any color space specifications in the JPEG2000 data are ignored.
      /// � If ColorSpace is absent, the color space specifications in the JPEG2000 data are used.
      ///   The Decode array is also ignored unless ImageMask is true.
      /// </summary>
      [KeyInfo(KeyType.NameOrArray | KeyType.Required)]
      public const string ColorSpace = "/ColorSpace";

      /// <summary>
      /// (Required except for image masks and images that use the JPXDecode filter)
      /// The number of bits used to represent each color component. Only a single value may be specified;
      /// the number of bits is the same for all color components. Valid values are 1, 2, 4, 8, and 
      /// (in PDF 1.5) 16. If ImageMask is true, this entry is optional, and if specified, its value 
      /// must be 1.
      /// If the image stream uses a filter, the value of BitsPerComponent must be consistent with the 
      /// size of the data samples that the filter delivers. In particular, a CCITTFaxDecode or JBIG2Decode 
      /// filter always delivers 1-bit samples, a RunLengthDecode or DCTDecode filter delivers 8-bit samples,
      /// and an LZWDecode or FlateDecode filter delivers samples of a specified size if a predictor function
      /// is used.
      /// If the image stream uses the JPXDecode filter, this entry is optional and ignored if present.
      /// The bit depth is determined in the process of decoding the JPEG2000 image.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string BitsPerComponent = "/BitsPerComponent";

      /// <summary>
      /// (Optional; PDF 1.1) The name of a color rendering intent to be used in rendering the image.
      /// Default value: the current rendering intent in the graphics state.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Optional)]
      public const string Intent = "/Intent";

      /// <summary>
      /// (Optional) A flag indicating whether the image is to be treated as an image mask.
      /// If this flag is true, the value of BitsPerComponent must be 1 and Mask and ColorSpace should
      /// not be specified; unmasked areas are painted using the current nonstroking color.
      /// Default value: false.
      /// </summary>
      [KeyInfo(KeyType.Boolean | KeyType.Optional)]
      public const string ImageMask = "/ImageMask";

      /// <summary>
      /// (Optional except for image masks; not allowed for image masks; PDF 1.3)
      /// An image XObject defining an image mask to be applied to this image, or an array specifying 
      /// a range of colors to be applied to it as a color key mask. If ImageMask is true, this entry
      /// must not be present.
      /// </summary>
      [KeyInfo(KeyType.StreamOrArray | KeyType.Optional)]
      public const string Mask = "/Mask";

      /// <summary>
      /// (Optional) An array of numbers describing how to map image samples into the range of values
      /// appropriate for the image�s color space. If ImageMask is true, the array must be either
      /// [0 1] or [1 0]; otherwise, its length must be twice the number of color components required 
      /// by ColorSpace. If the image uses the JPXDecode filter and ImageMask is false, Decode is ignored.
      /// Default value: see �Decode Arrays�.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string Decode = "/Decode";

      /// <summary>
      /// (Optional) A flag indicating whether image interpolation is to be performed. 
      /// Default value: false.
      /// </summary>
      [KeyInfo(KeyType.Boolean | KeyType.Optional)]
      public const string Interpolate = "/Interpolate";

      /// <summary>
      /// (Optional; PDF 1.3) An array of alternate image dictionaries for this image. The order of 
      /// elements within the array has no significance. This entry may not be present in an image 
      /// XObject that is itself an alternate image.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string Alternates = "/Alternates";

      /// <summary>
      /// (Optional; PDF 1.4) A subsidiary image XObject defining a soft-mask image to be used as a 
      /// source of mask shape or mask opacity values in the transparent imaging model. The alpha 
      /// source parameter in the graphics state determines whether the mask values are interpreted as
      /// shape or opacity. If present, this entry overrides the current soft mask in the graphics state,
      /// as well as the image�s Mask entry, if any. (However, the other transparencyrelated graphics 
      /// state parameters�blend mode and alpha constant�remain in effect.) If SMask is absent, the 
      /// image has no associated soft mask (although the current soft mask in the graphics state may
      /// still apply).
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string SMask = "/SMask";

      /// <summary>
      /// (Optional for images that use the JPXDecode filter, meaningless otherwise; PDF 1.5)
      /// A code specifying how soft-mask information encoded with image samples should be used:
      /// 0 If present, encoded soft-mask image information should be ignored.
      /// 1 The image�s data stream includes encoded soft-mask values. An application can create
      ///   a soft-mask image from the information to be used as a source of mask shape or mask 
      ///   opacity in the transparency imaging model.
      /// 2 The image�s data stream includes color channels that have been preblended with a 
      ///   background; the image data also includes an opacity channel. An application can create
      ///   a soft-mask image with a Matte entry from the opacity channel information to be used as
      ///   a source of mask shape or mask opacity in the transparency model. If this entry has a 
      ///   nonzero value, SMask should not be specified.
      /// Default value: 0.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Optional)]
      public const string SMaskInData = "/SMaskInData";

      /// <summary>
      /// (Required in PDF 1.0; optional otherwise) The name by which this image XObject is 
      /// referenced in the XObject subdictionary of the current resource dictionary.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Optional)]
      public const string Name = "/Name";

      /// <summary>
      /// (Required if the image is a structural content item; PDF 1.3) The integer key of the 
      /// image�s entry in the structural parent tree.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string StructParent = "/StructParent";

      /// <summary>
      /// (Optional; PDF 1.3; indirect reference preferred) The digital identifier of the image�s
      /// parent Web Capture content set.
      /// </summary>
      [KeyInfo(KeyType.String | KeyType.Optional)]
      public const string ID = "/ID";

      /// <summary>
      /// (Optional; PDF 1.2) An OPI version dictionary for the image. If ImageMask is true, 
      /// this entry is ignored.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Optional)]
      public const string OPI = "/OPI";

      /// <summary>
      /// (Optional; PDF 1.4) A metadata stream containing metadata for the image.
      /// </summary>
      [KeyInfo(KeyType.Stream | KeyType.Optional)]
      public const string Metadata = "/Metadata";

      /// <summary>
      /// (Optional; PDF 1.5) An optional content group or optional content membership dictionary,
      /// specifying the optional content properties for this image XObject. Before the image is
      /// processed, its visibility is determined based on this entry. If it is determined to be 
      /// invisible, the entire image is skipped, as if there were no Do operator to invoke it.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Optional)]
      public const string OC = "/OC";
    }
  }

  /// <summary>
  /// Helper class for creating bitmap masks (8 pels per byte).
  /// </summary>
  class MonochromeMask
  {
    private int sizeX;
    private int sizeY;
    private int writeOffset;
    private int byteBuffer;
    private int bitsWritten;

    /// <summary>
    /// Returns the bitmap mask that will be written to PDF.
    /// </summary>
    public byte[] MaskData
    {
      get { return maskData; }
    }
    private byte[] maskData = null;

    /// <summary>
    /// Creates a bitmap mask.
    /// </summary>
    public MonochromeMask(int sizeX, int sizeY)
    {
      this.sizeX = sizeX;
      this.sizeY = sizeY;
      int byteSize = ((sizeX + 7) / 8) * sizeY;
      maskData = new byte[byteSize];
      StartLine(0);
    }

    /// <summary>
    /// Starts a new line.
    /// </summary>
    public void StartLine(int newCurrentLine)
    {
      bitsWritten = 0;
      byteBuffer = 0;
      writeOffset = ((sizeX + 7) / 8) * (sizeY - 1 - newCurrentLine);
    }

    /// <summary>
    /// Adds a pel to the current line.
    /// </summary>
    /// <param name="isTransparent"></param>
    public void AddPel(bool isTransparent)
    {
      if (bitsWritten < sizeX)
      {
        // Mask: 0: opaque, 1: transparent (default mapping)
        if (isTransparent)
          byteBuffer = byteBuffer * 2 + 1;
        else
          byteBuffer = byteBuffer * 2;
        ++bitsWritten;
        if ((bitsWritten & 7) == 0)
        {
          maskData[writeOffset] = (byte)byteBuffer;
          ++writeOffset;
          byteBuffer = 0;
        }
        else if (bitsWritten == sizeX)
        {
          int n = 8 - (bitsWritten & 7);
          for (int i = 1; i <= n; ++i)
            byteBuffer *= 2;
          maskData[writeOffset] = (byte)byteBuffer;
        }
      }
    }

    /// <summary>
    /// Adds a pel from an alpha mask value.
    /// </summary>
    public void AddPel(int shade)
    {
      // NYI: dithering!!!
      AddPel(shade < 128);
    }
  }
}